Apparatus for improving accuracy of semi-automatic firearms



Apnl 30, 1968 c. P. GUSTIN 3,380,346

APPARATUS FOR IMPROVING ACCURACY OF SEMI-AUTOMATIC FIREARMS Filed June23, 1966 INVENTOR. CASSIUS P. GUSTIN ATTORNEYS United States PatentAPPARATUS FOR IMPROVING ACCURACY 0F SEMI-AUTOMATIC FIREARMS Cassius P.Gustin, 1729 Ohio Ave., Modesto, Calif. 95351 Filed June 23, 1966, Ser.No. 559,855 6 Claims. (Cl. 89-196) ABSTRACT OF THE DISCLOSURE Apparatus'for improving the accuracy of semi-automatic firearms in which a pairof studs is installed in the slide of a pistol at the barrel lug grooveso that the barrel lug contacts the studs when the pistol is in thebattery position.

The present invention relates to firearms utilizing the Browning lockedbreech auto-loading action such as the we1l-known Colt semi autom-atic.45 caliber pistol, Model of 1911, and concerns primarily a means forimproving the accuracy of such guns simply and inexpensively.

Conventional weapons of this type are manufactured with comparativelywide tolerances on the moving parts inforder to permit easy substitutionof broken or worn parts and to permit the pistols to function reliablyunder all kinds of adverse conditions, specifically, with much foreignmatter in their mechanism. Such wide clearances make for good, reliablemilitary weapons; but because the barrel of the weapon does not returnto precisely the same relative position within the slide at the battery,or firing, position, and as the sights are afiixed to the upper portionof the slide, these weapons are unsuitable for use as tar-get guns.

It is an object of the present invention to provide simple andinexpensive means for increasing the accuracy of 'weapons of the typedescribed by assuring that the barrel and slide retain the same relativeposition in registry with each other at battery after each firing.

.In the present invention there is provided a plurality of projectionsor studs on the inside of the slide located at the barrel lug recess.The addition of such projections -to the conventional weapon of the typedescribed results in the barrel of the weapon being constrained toassume the same position with respect to the slide and its sights aftereach shot. A feature and advantage of the invention is, therefore, thatgreatly improved accuracy is possible in the firing of the weapon, asthe barrel and sights are in substantially precisely the same alignmentafter each shot.

Another feature and advantage of the invention is that although theaccuracy of the weapon is greatly improved, the operating parts retaintheir wide clearances and thus parts may be freely substituted orreplaced without destroying the accuracy of the modified weapon.

Still another feature and advantage of the invention is that wear of theprojections or studs is minimal in the operation of the weapon so thatthe modified weapon retains its accuracy over long periods of use.

Other objects and advantages of the invention will become apparent uponreading the following specification and referring to the accompanyingdrawing in which similar characters of reference represent correspondingparts in each of the several views.

In the drawing:

FIG. 1 is a side view, partially cut away, of a pistol improved inaccordance with the invention;

FIG. 2 is a partial top view of the slide along the line 2--2 of FIG. 1;and

FIG. 3 is an enlarged section taken on line 3-3 of FIGS. 1 and 2.

3,380,346 Patented Apr. 30, 1968 Referring more particularly to thedrawing, shown at 10 is a .45 caliber semi-automatic pistol of thewellknown type referred to above. The weapon comprises a receiver orframe 11 which includes a handle 12 and a forward extending part 13. Theslide 14 is reciprocably mounted upon the frame. The front sight 22 andrear sight 23 are afiixed to the upper surface of the slide. The barrel15 is movably mounted upon the frame by means of lug 16, afiixed to thebarrel, and link 25. The barrel is held within the slide by means ofbarrel bushing 17.

When the pistol is at the battery position as illustrated in FIG. 1,squeezing the trigger 18 causes the hammer 19 to fall, firing thecartridge in the chamber (not shown). The slide recoils rearward. As itdoes, the barrel moves rearward and downward, disengaging the barrellugs 20 from their complementary grooves (not separately numbered) inthe slide. The spent cartridge is ejected through opening 21 shown inFIG. 2 as the slide completes its rearward motion. This rearward motionalso recocks the hammer 19.

The slide moves forward in counter-recoil motion from its far-rearwardrecoil position and picks up a fresh cartridge to insert it in thechamber (not shown). As the slide reaches its fully forward position thebarrel lugs 20 re-engage the barrel lug grooves in the slide to lock theslide and barrel together. Squeezing the trigger then repeats the cycle.

As may be seen more clearly in FIG. 3, the slide 14 is provided withlengthwise slots or ways 23 which ride upon corresponding lugs 24 formedin the frame 10. The barrel 15 is loosely received within a longitudinalrecess in the slide. Aflixed to the lower portion of the barrel is a lug16; pivotally connected to this lug is a link 25. The pin portion 26 ofthe slide stop assembly 27 passes through link 25. When the slide movesrearward in recoil, the barrel is carried with the slide for only aportion of its motion, because the barrel pivots upon the link 25,moving downward as it moves rearward.

The linkage consisting of lug 16, link 25, and pin 26 are manufacturedwith comparatively wide tolerances in conventional weapons. There arealso wide tolerances between the slide ways 23 and the receiver or framelugs 24, and between the barrel 15 and barrelbushing 17. As a result,when the barrel returns to the battery position after firing, with thebarrel lugs 20 locked in the barrel lug grooves, the barrel and slideare in rela tive-ly different positions with respect to each other,i.e., they are not in the same relative in-line registry or alignmentafter each firing.

The principal object of the present invention is to assure reproduciblealignment or registry of the barrel and slide after each firing of aweapon. As may best be seen in FIG. 3, an embodiment of the inventioncomprises a pair of small surface-area spacer elements or studs 28installed in the slide, each at an angle of approximately 45 to avertical plane bisecting the firearm. The studs are installed so thatthey pass into the forward barrel lug groove, contacting the forwardbarrel lug 20 when the firearm is in the battery position.

In a particular embodiment of the present invention, as described belowby way of example, two studs are installed in the slide at pointslocated so that the studs will enter the forward barrel lug recess inthe slide. This is accomplished by drilling two holes (31 wire gage)each 45 from the vertical plane bisecting the firearm, carefullythreading the holes using a 4 gun tap, then fitting headless screws intothe threaded holes until they just contact the barrel lug when theweapon is at battery position. The headless screws should preferablyhave flat ends and be made of alloy steel. If the slide is retractedapproximately /2 inch and the screws turned in approximately 4; turn or.0025 inch, the screws will then positively engage the forward barrellug when the slide is returned to the battery position. The slightpenetration of the adjusting screws into the forward barrel lug willcause the slide to lift in the receiver ways at the battery position,thus eliminating one source of inaccuracy in the firing of the gun. Thismay be clearly seen in FIG. 3. The upward pressure upon the barrelcaused by the action of the recoil spring upon the bottom barrel lugwill force the barrel into contact with the two projecting screw facesso that the barrel will assume the same relative position in registrywith the slide each time the barrel and slide return to the battery orfiring position, thus eliminating the other major source of inaccuracyin firing the weapon.

After the final adjustment to assure minimal relative movement of theparts of the firearm, the screws may be locked in position by deformingthe threads at the outside face of each screw by means of a center punchor similar tool. Final locking of the screws is accomplished by weldingor brazing or similarly affixing the screw to the threaded hole on theoutside surface of the slide. The slide may be returned to its originalappearance thereafter by filling in the threaded holes above the screwsby means of welding, brazing, or other similar processes; restoring theoriginal contour of the slide by conventional machine or hand processes;then polishing and rebluing the slide.

These and other modifications of my invention may be practiced, it beingunderstood that the form of my invention, as described above, is to betaken as a preferred example of the same. Such description has been byway of illustration and example for purposes of clarity ofunderstanding. Various changes and modifications may be made withoutdeparting from the spirit of my invention as limited only by the scopeof the appended claims.

I claim:

1. In a semi-automatic firearm of the type having a frame; a slidereciprocably mounted on said frame; a barrel mounted on said frame anddisposed to move between a battery position locked to said slide and arecoil position disengaged from said slide; the interior of said slidehaving a lug groove transverse the longitudinal axis of said slide; saidbarrel having a raised lug disposed to fit within said lug groove whensaid slide and said barrel are at the battery position and said lug andsaid groove disposed to be disengaged from each other to permit theslide to move rearwardly while said barrel is in the recoil position;the combination with said barrel and said slide of a plurality of smallsurface-area spacer elements disposed at said lug groove and betweensaid barrel and said slide to force said barrel into repeatablealignment with said slide each time said barrel and slide are moved intobattery position.

2. The invention of claim 1 wherein said spacer ele- 4 ments include twomembers fixedly attached to said slide at said lug groove and positionedto extend inwardly from the inner surface of the groove whereby saidbarrel lug is engaged at two spaced-apart points when said firearm is atbattery position to space the lug from direct engagement with the innersurface of said groove.

3. The invention of claim 1 wherein said slide carries rigidly therewithfront and rear sights and wherein said spacer elements comprise twomembers fixedly attached to said slide at said lug groove, said memberssymmetrically positioned about a plane which includes the longitudinalaxis of said slide along the line of the sights and the longitudinalaxis of the barrel, said members extending inwardly adjacent said barrellug whereby said barrel lug is engaged by said members when said firearmis at battery position.

4. In a semi-automatic firearm of the type having a frame; a slidereciprocably mounted on said frame; a barrel mounted on said frame anddisposed to move between a battery position locked to said slide and arecoil position disengaged from said slide; the interior of said slidehaving 2. lug groove transverse the longitudinal axis of said slidehaving a lug groove transverse the longitudinal axis of said slide; saidbarrel having a raised lug displosed to fit within said lug groove whensaid slide and said barrel are at the battery position and said lug andsaid groove disposed to be disengaged from each other to permit theslide to move rearwardly while said barrel is in the recoil position;and a pair of studs fixedly attached to said slide, said studsprojecting inwardly and contacting said barrel lug at two angularlyspaced-apart points.

5. The invention of claim 4 wherein said slide carries front and rearsights rigidly therewith and wherein said studs are symmetricallypositioned about a plane through the line of the sights and bisectingthe firearm.

6. In a semi-automatic firearm the combination of a frame, a slideslidably attached to said frame, said slide having a recess transverseits longitudinal axis, a barrel having a raised barrel lug upon itsupper surface, said barrel movably mounted within said slide so thatsaid barrel lug is disposed within said slide recess when said firearmis at firing position, a plurality of spacer elements disposed betweensaid barrel lug and said transverse recess whereby said barrel and saidslide are held in repeatable alignment whenever said firearm is infiring position.

References Cited UNITED STATES PATENTS 3,252,237 5/1966 Korzeniewski89--l96 X BENJAMIN A. BORCI-IELT, Primary Examiner.

S. C. BENTLEY, Assistant Examiner.

